COMPUTING TOPIC COMPONENT ONE parts of a computer system Flashcards
What is the purpose of a computer?
to take data, process it, then output it
Why were computers built?
to help process data and complete tasks more efficiently than humans
What does a computer system consist of?
hardware and software that work together to process tasks
What is hardware?
the physical stuff that makes up your computer
What is software?
the programs or applications that a computer system runs
What are external pieces of hardware called?
peripherals
How are there many types of computers sytems?
- range from small (calculators) to big (supercomputers used by banks)
- general purpose (PCs) to dedicated systems (controlling traffic lights)
What are emedded systems?
computers built into other devices e.g. microwaves and TVs, they are usually dedicated systems
What do embedded systems do?
- often used as control machinery, they monitor and control the other parts to produce a desired result
- as they’re dedicated to a single task, they are usually easier to design, cheaper to produce and more efficient at their job than a general purpose computer
What does the power supply do?
provide power to motherboard, optical and hard drives, and other hardware
What does a case cooling fan do?
extracts hot air from inside the computer case
What does the CPU heat sink and cooling fan do?
keeps the CPU at a steady temperature
What does the CPU do?
processes all the data and instructions that make a computer work
What does the Hard Disk Drive do?
provide internal secondary storage
What does the motherboard do?
the main circuit board in the computer where all the hardware is connected
What does the optical drive do?
the reading/writing of optical disks
What does the processing power of the CPU depend on?
- clock speed
- number of cores
- cache size
What does the CPU architecture describe?
- the main components of the CPU
- how they interact with each other
- how they interact with other parts of the system
What are the three main parts of the CPU?
- the control unit
- the arithmetic logic unit
- the cache
What does the control unit do?
- in overall control of the CPU, main job is to execute program instructions following the fetch-decode-execute cycle
- controls the flow of data inside and outside the CPU
What does the arithmetic logic unit do?
- does all the calculations
- simple addition, subtraction, multiplication, division and compares the size of numbers
- performs logic operations such as AND, OR, NOT
- performs binary shifts
What does the cache do?
- very fast memory in CPU, slower than registers but faster than RAM
- stores regularly used data so that the CPU can access it quicker
- when the CPU requests data, it will first check the cache to see if it’s there, if not then it will check the RAM
- caches have a very low capacity and are expensive compared to the RAM
What are the different levels of cache memory?
- L1, L2, L3
- L1 is quickest but holds the least, L2 is slower but holds more, L3 is slowest but holds the most
What are the CPU registers?
- temporarily hold tiny bits of data needed by the CPU
- they are super quick to read/write to, much quicker than any form of memory
What does the Von Neumann architecture?
describes a system where the CPU runs programs stored in the memory
What do programs consist of in the Von Neumann architecture?
instructions and data which are stored in the memory addresses
What register does the control unit contain?
program counter
What register does the arithmetic logic unit contain?
accumulator
What other registers are in the CPU?
- memory address register
- memory data register
What is the function of the program counter?
holds the memory address of the instruction for each cycle
What is the function of the memory address register?
- holds any memory address about to be used by the CPU
- the address might point to data or an instruction
What is the function of the memory data register?
- holds the actual data or instruction
- may have been fetched from the memory or waiting to be written to the memory
What is the function of the accumulator?
stores intermediate results of calculations in the ALU
What does the memory hold in Von Neumann architecture?
holds the program instructions and the program data
What is one feature of the Von Neumann architecture?
only uses one memory for both data and instructions
What happens in the fetch instruction?
- copy memory address from the program counter to the MAR
- copy the instruction stored in the MAR address to the MDR
- increment the program counter to point to the address of the next instruction ready for the next cycle
What happens in the decode instruction?
- instruction in the MDR is decoded by the control unit
- control unit may then prepare for next step e.g. loading values into MAR or MDR
What happens in the execute instruction?
- the instruction is performed
- this could be: load data from memory, write data to memory, do a calculation or logic operation using ALU, change the address in the program counter, or halt the program
What is the difference between the program counter and the MAR?
- program counter starts off each cycle by pointing to the instruction
- MAR has to process all memory address for both data and instructions which means its value might change several times each cycle
What does the memory contain?
all the instructions that the CPU follows
What is the RAM used as?
the main memory in the computer
What is the main memory?
where all data, files and programs are stored while they’re being used
How is RAM used?
- when the computer boots up, the OS is copied from secondary storage to the RAM
- when applications, documents or files are opened, they are copied from secondary storage to RAM and stay in the RAM until they are closed
What is the speed of RAM like?
slower than the CPU cache but faster than secondary storage
How is virtual memory created?
- computers have a limited amount of RAM, as applications are opened, the RAM fills with data
- when RAM is full, computer needs somewhere else to put application data
- it moves data that hasn’t been used recently to a location on secondary storage known as virtual memory
When is virtual memory needed?
if there are too many applications open, or there is a memory-intensive application, or both
How are transfer rates slower when using virtual memory?
- if the CPU needs to read data from virtual memory, it must transfer the data back to RAM
- this is slow as data transfer rates are slower on secondary storage than on RAM
How does using virtual memory make a computer slow to respond?
- when switching between applications, while data for one application is swapped for another in virtual memory
- when using a memory-intensive program, due to data constantly moving between virtual memory and RAM just to keep the program running
What is the BIOS?
a type of firmware, hardware-specific software built into a device